The present invention relates to engine tachometers, and more particularly to a tachometer which is designed to measure the speed in revolutions per minute of a Diesel engine during the period of idle adjustment.
A known type of idle adjusting tachometer is designed so that as will be the case with gasoline engine tachometers, the primary or secondary voltage of the ignition coil is detected and the engine rpm is measured from the detection signal. However, and this prior art device has the disadvantage of being not suitable for use in vehicles equipped with Diesel engines.